In the robot programming, operating tasks of a workpiece may generally be defined in a coordinate system such as a flange coordinate system of a robot, so the relationship between a tool coordinate system fastened on a tool and a flange coordinate system where an end joint for fastening the tool should be required firstly before processing the workpiece, that is, the tool coordinate system is calibrated. The calibration of the tool coordinate system is to determine a coordinate of the tool center point in the flange coordinate system and coordinate axis directions of the tool coordinate system relative to the flange coordinate system. A four-point calibration method may be generally adopted during the calibration process of the tool coordinate system in the art to determine the coordinate of the tool center point in the flange coordinate system. In specific, the four-point calibration method is to make the tool center point of a tool coordinate system to be calibrated move in four different directions to a same calibration reference point, such that rotation angles of each joint of the robot during four movement of the tool center point may be acquired; and then acquire the coordinate value of the tool center point in the flange coordinate system according to an acquired rotation angle and four-point calibration algorithm.
What have been found by the applicant of the present disclosure, the tool center point are required to move in four directions to the calibration reference in the four-point calibration method of the art, and many movement paths are required to be selected. That is to say, during the practical calibration operation, at least four times to operate the tool center point move to the calibration reference point will be required in calibration of each tool center point, calibration operations is so complicated that the calibration efficiency of the tool coordinate system is low, and further the processing efficiency of the workpiece will be affected.